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    <title>Document</title>
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<script>
    var num = 10;
    var str = "10";
    //两个等号判断值是否相等
    console.log(num == str);
    //三个等号是先判断变量的类型，然后再判断变量的值，
    //只有变量的类型和值都相等时结果为true
    console.log(num === str);

    var x = 3;
    var y = 3;
    var z = "3";
    alert(x == y);  //ture
    alert(x === y); //ture
    alert(x === z); //false
</script>
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